The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 22, 2014
Filed:
Jan. 12, 2012
Kinobu Osakabe, Tokyo, JP;
Hideki Isono, Tokyo, JP;
Katsuyuki Iwata, Tokyo, JP;
Shinji Eda, Tokyo, JP;
Kenichiro Terada, Tokyo, JP;
Kinobu Osakabe, Tokyo, JP;
Hideki Isono, Tokyo, JP;
Katsuyuki Iwata, Tokyo, JP;
Shinji Eda, Tokyo, JP;
Kenichiro Terada, Tokyo, JP;
Hoya Corporation, Tokyo, JP;
Abstract
A glass substrate for a magnetic disk of the invention is a disk-shaped glass substrate for a magnetic disk where the substrate has a main surface and end face and is subjected to chemical reinforcement treatment, and is characterized in that the penetration length in the uppermost-portion stress layer on the main surface is 49.1 μm or less, and that assuming that an angle between the main surface and compressive stress in the stress profile by a Babinet compensator method is θ, a value y of {12·t·ln(tan θ)+(49.1/t)} is the penetration length in the uppermost-portion stress layer or less.